Lucrezia is the fifth child of the Medici family in Florence. She is small for her age and possesses striking flame-colored hair. Unlike her socially adept siblings, she prefers eating on the floor, observing the palace's captive tiger, and creating intricate paintings. Forced into a dynastic marriage at a young age, she relies on her innate toughness and private rebellions to maintain her sense of self in a highly controlled court environment.

Alfonso is the powerful ruler of Ferrara. He presents a refined and highly educated exterior, commissioning renowned artists and unique musicians for his court. Beneath his civilized manners, he operates with extreme paranoia and ruthlessness. Driven by a desperate, secretive need to produce an heir and protect his bloodline from rival claims, he demands absolute perfection and submission from those around him.

Eleanora is the duchess consort of Florence. She possesses a restless, strategic mind and a strong desire to organize the world around her. She manages her household with extreme precision, leaving no room for idleness in her children's schedules. Though she enjoys a relatively equal partnership with her husband, she strictly enforces traditional expectations on her daughters to protect the family's political standing.

Cosimo is the ruler of Florence and a grand patron of the arts. He maintains an outgoing, congenial public temperament but remains constantly aware of the dangers of his position, taking precautions like wearing chainmail beneath his clothing. While he is unusually faithful to his wife and values her counsel, he is thoroughly pragmatic when arranging dynastic marriages for his children.

Maria is the eldest Medici child. She possesses robust health, social fluency, and conventional accomplishments in music and dancing. She fully embraces her intended role as the future Duchess of Ferrara. Her sudden, fatal lung illness creates a void in the dynastic alliance that permanently alters her family's trajectory.

Isabella is the older sister of Lucrezia and the favored daughter of Cosimo. She possesses her mother's dark hair and adapts easily to the expectations of Renaissance Italian womanhood. She is flirtatious, acutely aware of her social standing, and openly envious of the lavish jewels her sister receives from the Duke of Ferrara.

Sofia is the Neapolitan nurse who manages the Medici nursery and provides maternal warmth to the children. She is fiercely protective of Lucrezia and teaches the young girl her native Neapolitan dialect. Recognizing her lack of institutional power, she uses cunning domestic strategies to protect her charges from unwanted fates.

Emilia is a young servant girl and the daughter of Lucrezia's original wet nurse. She shares Lucrezia's fair-haired physical appearance but occupies a vastly different social station, initially working in the kitchens before being appointed to serve the new Duchess. She is resourceful, loyal, and observant, utilizing her largely invisible status as a servant to gather valuable information.

Leonello is Alfonso's deeply trusted consigliere, educated alongside the Duke and fiercely dedicated to his interests. He is an imposing presence with lion-colored hair and a ruthless disposition. He resents any outside influence on Alfonso and actively enforces the Duke's severe decrees through intimidation, violence, and constant surveillance.

Jacopo is an orphaned assistant painter working under Il Bastianino in Ferrara. He is highly talented, specifically skilled at painting cloth and fine details. He purposefully allows others to believe he is mute to gather information discretely. He communicates in his native Neapolitan dialect and forms a quiet, profound connection with Lucrezia over their shared passion for art and their mutual feeling of isolation.

Il Bastianino is a renowned Mannerist painter commissioned by Alfonso to create a lasting image of the new Duchess. In reality, he is a dilettante who drinks heavily and delegates the vast majority of the detailed work to his assistants. During portrait sittings, he behaves unprofessionally, frequently inventing excuses to touch and physically adjust his young subject.

Elisabetta is Alfonso's younger sister, an unmarried woman with dark eyes and high cheekbones. At twenty-six, she is considered past marriageable age, a situation that perfectly suits her brother's desire to prevent rival heirs. She openly resents Alfonso's controlling nature and seeks personal freedom through illicit romance, initially befriending her young new sister-in-law.

Nunciata is the younger sister of Alfonso, characterized by her short, stout stature and dull clothing. Lacking her sister's beauty and romantic inclinations, she secures her position at court by acting as her brother's reliable informant. She delights in monitoring other women, dropping pointed remarks about fertility, and deliberately interfering with Lucrezia's independence.

Vitelli is Cosimo di Medici's trusted adviser and right-hand man. He is a pragmatic political operative who manages both the exotic animals in the palazzo and the delicate negotiations regarding the family's dynastic marriages. He approaches matters of state and family with clinical detachment.

Ercole Contrari is a head guardsman at the Ferrara court. Despite his lower social rank, he treats Elisabetta with immense gentleness and respect, representing the kind of egalitarian relationship Lucrezia quietly desires for herself. His position makes his romance extremely dangerous.

Maurizio is an assistant painter working alongside Jacopo in Il Bastianino's studio. He is highly observant of the dangerous court dynamics and quietly warns others about Alfonso's volatile ability to switch personalities instantly.

Pietro is the husband of Isabella di Medici. Through his marriage, he allows Isabella to remain in Florence, securing her favorable position near her father and highlighting the disparate fates of the Medici daughters.

Clelia is a high-born lady-in-waiting at the Ferrara court. She is stationed with Lucrezia to monitor the new Duchess, representing the constant surveillance and complete lack of privacy inherent in Ferrarese court life.